SwipeTransitionEffectLib — Plan9Basic Documentation

Overview

SwipeTransitionEffectLib creates a page-fold/swipe transition where the page corner is "pulled" to a position, revealing the target image underneath — like turning a page in a book. Wraps the FireMonkey TSwipeTransitionEffect component.

Property	Details
Library	`SwipeTransitionEffectLib`
Prefix	`swipetrans_`
Wraps	`TSwipeTransitionEffect`
Functions	20
Type	Transition effect

Category	Count	Description
Creation / Destruction	2	Create and free effect
Target Image	4	Set/get/load target bitmap
Mouse Point	4	Get/set X and Y fold positions
Fold Depth	2	Get/set fold intensity
Effect Control	4	Enabled and trigger get/set
Error Handling	4	Error codes and messages

⚠ Pixel Coordinates: MousePoint uses pixel values, not normalized 0–1 ranges. For a 200×150 image, MouseX ranges from 0 to 200+ and MouseY from 0 to 150+.

📖 Page Turn: The page folds from the top-left corner (default). Moving the MousePoint diagonally away from that corner creates the fold. The target image is revealed under the lifted page — like turning a real page.

Cross-Platform Support

Platform	Support
Windows	✅ Full support
Linux	✅ Full support
Android	✅ Full support

Creation & Destruction

swipetrans#(parent#)

Creates a new swipe transition effect attached to the specified visual control.

Parameter	Type	Description
`parent#`	Pointer	Target visual control
Returns	Pointer	Effect handle, or 0 on failure

swipetrans_free(effect#)

Destroys the effect and releases associated resources.

Error Handling

Function	Signature	Description
`swipetrans_error()`	`swipetrans_error@`	Returns last error code (0 = none)
`swipetrans_errormsg$()`	`swipetrans_errormsg$@`	Returns last error message
`swipetrans_strerror$(code)`	`swipetrans_strerror$@n`	Converts error code to text
`swipetrans_clearerror()`	`swipetrans_clearerror@`	Clears the error state

Target Image

The target image is revealed underneath the folded page.

Function	Signature	Description
`swipetrans_target#(effect#, bitmap#)`	`swipetrans_target#@##`	Sets target from bitmap pointer
`swipetrans_target#(effect#)`	`swipetrans_target#@#`	Gets target bitmap pointer
`swipetrans_loadtarget#(effect#, url$)`	`swipetrans_loadtarget#@#$`	Loads target from URL or file
`swipetrans_targetfromimage#(effect#, img#)`	`swipetrans_targetfromimage#@##`	Sets target from image control

Mouse Point

Controls where the page corner is "pulled" to, in pixel coordinates. The page folds from the top-left corner by default, so moving the point diagonally toward the bottom-right creates the fold.

Function	Signature	Description
`swipetrans_mousex#(effect#, value)`	`swipetrans_mousex#@#n`	Set X position (pixels)
`swipetrans_mousex(effect#)`	`swipetrans_mousex@#`	Get X position
`swipetrans_mousey#(effect#, value)`	`swipetrans_mousey#@#n`	Set Y position (pixels)
`swipetrans_mousey(effect#)`	`swipetrans_mousey@#`	Get Y position

MouseX, MouseY	Effect
`0, 0`	No fold (corner at origin)
`imgW/2, imgH/2`	Fold to center (halfway turned)
`imgW, imgH`	Full page turn (corner at opposite end)

Fold Depth

Controls how curved or folded the page appears. Higher values create a more dramatic curl.

Function	Signature	Description
`swipetrans_deep#(effect#, value)`	`swipetrans_deep#@#n`	Set fold depth (0–100)
`swipetrans_deep(effect#)`	`swipetrans_deep@#`	Get depth

Value	Effect
`0–10`	Nearly flat fold
`20–40`	Natural page curl (recommended)
`50–100`	Very dramatic fold/curl

Effect Control

Function	Signature	Description
`swipetrans_enabled#(effect#, value)`	`swipetrans_enabled#@#n`	Enable (1) or disable (0)
`swipetrans_enabled(effect#)`	`swipetrans_enabled@#`	Gets enabled state
`swipetrans_trigger#(effect#, trigger$)`	`swipetrans_trigger#@#$`	Sets trigger string
`swipetrans_trigger$(effect#)`	`swipetrans_trigger$@#`	Gets trigger string

Complete Examples

Example 1: Interactive Page Fold

╯ swipe-control.bas─◻✕
let frm# = Pointer#(0)
let img# = Pointer#(0)
let swipe# = Pointer#(0)
let trkX# = Pointer#(0)
let trkY# = Pointer#(0)
let trkDeep# = Pointer#(0)
let lblX# = Pointer#(0)
let lblY# = Pointer#(0)
let lblDeep# = Pointer#(0)
let imgW = 200
let imgH = 150

frm# = form#("Swipe Control", 500, 500)

img# = image#(frm#)
image_bounds#(img#, 150, 20, imgW, imgH)
image_load#(img#, "https://picsum.photos/200/150?random=1")

swipe# = swipetrans#(img#)
swipetrans_loadtarget#(swipe#, "https://picsum.photos/200/150?random=2")
swipetrans_mousex#(swipe#, 100)
swipetrans_mousey#(swipe#, 75)
swipetrans_deep#(swipe#, 30)

lblX# = label#(frm#, "Mouse X: 100", 30, 190)
trkX# = trackbar#(frm#)
trackbar_bounds#(trkX#, 30, 215, 440, 25)
trackbar_max#(trkX#, imgW)
trackbar_value#(trkX#, 100)
trackbar_onchange#(trkX#, "OnX")

lblY# = label#(frm#, "Mouse Y: 75", 30, 260)
trkY# = trackbar#(frm#)
trackbar_bounds#(trkY#, 30, 285, 440, 25)
trackbar_max#(trkY#, imgH)
trackbar_value#(trkY#, 75)
trackbar_onchange#(trkY#, "OnY")

lblDeep# = label#(frm#, "Deep: 30", 30, 330)
trkDeep# = trackbar#(frm#)
trackbar_bounds#(trkDeep#, 30, 355, 440, 25)
trackbar_max#(trkDeep#, 100)
trackbar_value#(trkDeep#, 30)
trackbar_onchange#(trkDeep#, "OnDeep")

form_show(frm#)

function OnX(sender#) local v
  let v = trackbar_value(trkX#)
  swipetrans_mousex#(swipe#, v)
  label_text#(lblX#, "Mouse X: " + str$(v))
endfunction

function OnY(sender#) local v
  let v = trackbar_value(trkY#)
  swipetrans_mousey#(swipe#, v)
  label_text#(lblY#, "Mouse Y: " + str$(v))
endfunction

function OnDeep(sender#) local v
  let v = trackbar_value(trkDeep#)
  swipetrans_deep#(swipe#, v)
  label_text#(lblDeep#, "Deep: " + str$(v))
endfunction

Example 2: Animated Page Turn

╯ page-turn.bas─◻✕
let frm# = Pointer#(0)
let img# = Pointer#(0)
let swipe# = Pointer#(0)
let tmr# = Pointer#(0)
let btn# = Pointer#(0)
let progress = 0
let imgW = 200
let imgH = 150

frm# = form#("Page Turn", 400, 350)

img# = image#(frm#)
image_bounds#(img#, 100, 30, imgW, imgH)
image_load#(img#, "https://picsum.photos/200/150?random=1")

swipe# = swipetrans#(img#)
swipetrans_loadtarget#(swipe#, "https://picsum.photos/200/150?random=2")
swipetrans_mousex#(swipe#, 0)
swipetrans_mousey#(swipe#, 0)
swipetrans_deep#(swipe#, 30)

tmr# = timer#()
timer_interval#(tmr#, 30)
timer_enabled#(tmr#, 0)
timer_ontimer#(tmr#, "Animate")

btn# = button#(frm#, "Turn Page")
button_bounds#(btn#, 140, 210, 120, 30)
button_onclick#(btn#, "StartTurn")

form_show(frm#)

function StartTurn(sender#)
  progress = 0
  timer_enabled#(tmr#, 1)
  button_enabled#(btn#, 0)
endfunction

function Animate(sender#) local x, y
  progress = progress + 0.03
  let x = progress * imgW
  let y = progress * imgH
  swipetrans_mousex#(swipe#, x)
  swipetrans_mousey#(swipe#, y)
  
  if progress >= 1 then
    timer_enabled#(tmr#, 0)
    button_enabled#(btn#, 1)
  endif
endfunction

Quick Reference

Function	Signature	Description
CREATION & DESTRUCTION
`swipetrans#(parent#)`	`swipetrans#@#`	Create effect
`swipetrans_free(effect#)`	`swipetrans_free@#`	Destroy effect
TARGET IMAGE
`swipetrans_target#(effect#, bitmap#)`	`swipetrans_target#@##`	Set target bitmap
`swipetrans_target#(effect#)`	`swipetrans_target#@#`	Get target bitmap
`swipetrans_loadtarget#(effect#, url$)`	`swipetrans_loadtarget#@#$`	Load target
`swipetrans_targetfromimage#(effect#, img#)`	`swipetrans_targetfromimage#@##`	Target from image
MOUSE POINT
`swipetrans_mousex#(effect#, value)`	`swipetrans_mousex#@#n`	Set X (pixels)
`swipetrans_mousex(effect#)`	`swipetrans_mousex@#`	Get X
`swipetrans_mousey#(effect#, value)`	`swipetrans_mousey#@#n`	Set Y (pixels)
`swipetrans_mousey(effect#)`	`swipetrans_mousey@#`	Get Y
FOLD DEPTH
`swipetrans_deep#(effect#, value)`	`swipetrans_deep#@#n`	Set fold depth (0–100)
`swipetrans_deep(effect#)`	`swipetrans_deep@#`	Get depth
EFFECT CONTROL
`swipetrans_enabled#(effect#, value)`	`swipetrans_enabled#@#n`	Enable/disable
`swipetrans_enabled(effect#)`	`swipetrans_enabled@#`	Get enabled state
`swipetrans_trigger#(effect#, trigger$)`	`swipetrans_trigger#@#$`	Set trigger
`swipetrans_trigger$(effect#)`	`swipetrans_trigger$@#`	Get trigger
ERROR HANDLING
`swipetrans_error()`	`swipetrans_error@`	Last error code
`swipetrans_errormsg$()`	`swipetrans_errormsg$@`	Last error message
`swipetrans_strerror$(code)`	`swipetrans_strerror$@n`	Code to text
`swipetrans_clearerror()`	`swipetrans_clearerror@`	Clear error state

Library	Description
`SlideTransitionEffectLib`	Slide transition
`FadeTransitionEffectLib`	Cross-fade transition
`DropTransitionEffectLib`	Drop transition